Electrical current control and visual interpretation of electrical current



ELECTRICAL CURRENT CONTROL AND VISUAL INTERPRETATION OF ELECTRICAL CURRENT Filed Feb. 8, 1941 March 3, 1942; R. D. BURCHFIELD I 2,275,233

Patented Mar. 3, 1942 UNITED STATES PATENT OFFICE ELECTRICAL CURRENT CONTROL AND VIS- UAL INTERPRETATION OF ELECTRICAL CURRENT Claims.

This invention pertains to new and improved arrangements for and procedure of controlling electrical changes, and for translating electrical currents into visible effects, particularly, changes or variations in frequency or amplitude.

In another aspect, my invention pertains to a system or systems for automatically synchronizing light in accordance with variations of audio frequency current as provided by a suitable agency such as a radio, phonograph, etc.

The invention is in one sense an improvement of the system shown in my United States Patent No. 2,131,934 in which I disclose an arrangement for giving a luminous interpretation of music, etc., according to a frequency analogy of sound and light. In the present arrangement, I have been able to prevent flicker and to smooth or iron out variations in light changes and to increase luminous output. I have also been able to provide an amplitude analogy of sound and light.

The present invention, although especially adapted for use in connection with a radio receiving circuit or a phonograph reproducing circult, is not limited to such applications and may be used in many other arrangements which will be apparent to those skilled in the art from the present disclosure.

In view of these considerations, it has been an object of my invention to provide a new and improved system or procedure for, in effect, interpreting current variations by means of light or color.

Another object has been to devise a system that will achieve luminous effects that will give substantially the impression of music-made-visible.

A further object of my invention is to provide an automatically synchronized color organ having a better and smoother luminous output.

These and many other objects of my invention will appear to those skilled in the art from the drawing, the description, and the appended claims.

In the drawing:

Figure 1 is a circuit diagram showing a system embodying my invention particularly as applied to frequency or pitch color interpretation of an audio frequency output;

Figure 2 is a circuit diagram illustrating another form of my invention combining amplitude and frequency color interpretation, and thus, also illustrating a circuit for amplitude interpretation as distinct from frequency variation;

Figure 3 is a somewhat diagrammatic vertical elevation showing a specific lamp arrangement for utilizing current supplied and controlled in accordance with the present invention;

Figure 4 is a somewhat diagrammatic circuit representing applicants new and improved idea employing filament voltage variation in a vacuum tube as distinguished from ordinary grid characteristic variation for gradual control purposes to iron and smooth out rapid variations of current. In Figures 1 and 2, the arrangement is applied to a heater type of cathode control; in Figure 4, C represents current input from a control unit such as I0, and D represents the current output to a controlled circuit or unit such as 30 or 50.

In carrying out my invention, referring, for example, to Figure 1, I preferably provide a suitable power amplifier of low impedance output by a circuit or unit It. In like manner, I provide a suitable power rectifier arrangement circuit or unit that, as shown in Figure 1, includes a full wave rectifier tube 26 and a transformer 22 having a three-part or tapped secondary 23, 24, and 25 for providing suitably rectified alternating current to the unit Ill. The transformer secondary 25 is connected at b to the filament portion of the tube I5. An ordinary 110volt alternating current supply 2| may be utilized; taps are provided for an auto-transformer 44 to supply approximately 220 volts to colored lamps 4|, 42, and 43, as shown.

An output transformer supplies low voltage audio current at low impedance to a frequency control, color-interpreting circuit that has diode-connected control tubes 3|, 32, and 33, and colored lamps 4|, 42, and 43; the latter are connected in the respective anode circuits of the control tubes. Impedances 34 and 36 and condensers and 31 provide the respective control tubes 3|, 32, and 33 with a scaled selected range of frequencies suitable for actuating the lamps 4|, 42, and 43.

The audio output of the amplifier circuit In causes the lamps 4|, 42, and 43 to light in accordance with frequency changes of a current passing through an impedance matching output transformer l1. Due to the presence of the filter inductances and capacities 34-3|, inclusive, in the control-tube network, the system is frequency discriminative such that each lamp responds to its own range of audio frequencies, the first lamp 4| being adapted to light up at a lower sound pitch or frequency, the second 42 at an intermediate pitch, and the third at higher pitches. When each lamp is of a different color such as red, green, and blue, respectively, I have an apparatus for a synchronized colored light interpretation of sound and music that may be termed an automatic color organ.

The present arrangement provides for a marked increase of power and for the elimination of objectionable fiicker that occurred in earlier arrangements. I devised the idea of replacing each lamp of an arrangement such as shown in Figure 1 of the circuit of my patent, with the filament of a suitable rectifier tube. Each tube is then used as a varying resistance in series with one or more 110 volt lamps of sizable wattage.

Since the filaments of the control tubes 31, 32, and 33 are excited by amplified and frequencysegregated audio signal currents, the tubes effective conductances will vary with the signal, the conductance of each depending upon the amount of its particular frequency present in the signal at any instant. Thus, larger wattage lamps, such as 15 watts as compared to 2 or 3 watts of my early arrangement, will follow music just as faithfully as did the smallerlamps, and the thermal lag of the filaments of the control tube eliminates fiicker. The circuit diagram of Figure 1 illustrates a form of this arrangement as particularly applied to a frequency selective system.

I found that a suitable tube for the control function was a '7l-A with the grid and plate connected together at the socket to make it a rectifier or diode; this tube combines a suitably low filament current with a high effective conductance. To relieve the control tubes 3|, 32, and 33 of part of the lamp circuit load, I employed resistances 38, 39 and 4D in parallel or shunt with their filaments and plates. The resistances were adjusted to bring the lamps 4l-43 to a dull glow, preferably not visible on a screen when no signal is present, that is, when the control tubes have an infinite resistance.

I found that this arrangement of shuntresistors also reduces the plate voltage across the control tubes, lessening the strain on them. In lieu of one or more shunt resistors, I employed a series pair of lamps; for example, lamps of 110 volts, 5 watts each, one pair being connected in shunt or parallel with each control tube. During operation, the main lamps Al, 42, and 43 would glow dimly with no signal. When a signal was applied, the control tubes functioned as expected, and the main lamps followed by their change in brilliance the changing signal intensities representing music, for example. The pair of series-connected shunt lamps, however, which took the place of the resistances 38, 39, and 40,

underwent inverse changes in brilliancy in thatwhen the control tube space current flowed, the drop across the particular tube decreased, dimming the shunt lamps.

It will be apparent'to those skilled in the art that this latter arrangement is an elementary color organ of an entirely new type and that it is amplitude as distinguished from frequency-actuated. Lamps used as shunt resistances can thus be utilized in a visual ensemble. An arrangement of the latter type in preferred form is shown below the broken line AA of Figure 2 of the draw- The portion of this circuit above the line B-B corresponds to the arrangement shown in Figure l. The combined arrangement provides a dual purpose circuit wherein both frequency and amplitude variations are recorded by means of color or light intensity. For example, as shown in Figure 3, lamps I, 2, 3, and 4 may be positioned in translucent cylinders of glass, plastic, or other suitable material disposed about a translucent bowl within which are disposed the previouslymentioned colored lamps 4|, 42, and 43.

Although to the unaccustomed eye, the singleacting (color change with pitch) system is adequate for musical accompaniment, the dual color organ seems many times more remarkable. The lamps of the supplementary group are disposed as indicated in Figure 2 and are served by a circuit similar to the first described in connection with Figure 1, but functioning, as pointed out, according to the amplitude of the audible music. The lamp pairs 2-4 gradually light up in succession as the sound amplitude increases, and vice versa. The light pair I is lit with zero signal and dims as pair 2 begins to brighten. The effect of this action is one of mounting and subsiding motion besides color change. In this manner, crescendos and diminuendos are strikingly interpreted. I have found the following lamp characteristics satisfactory:

volt lamps 1:7 watt--red or purple. 2:10 wattblue. 3 15 watt-green. 4:15 watt-yellow.

I prefer pastel or pale colors.

It will be apparent that suitable switches interposed along the broken lines BB will serve to isolate the frequency control circuit and make the circuit entirelydependent upon amplitude variations, referring to Figure 2. On the other hand, switches interposed along the line AA will enable the operator to cut out the amplitude portion of the circuit as represented by the amplifier l0 and amplitude unit 50. It will be noted that the so-called amplitude stage was represented by [0 and 50 is substantially identical to the previously described frequency stage In and 30 except that no impedances are employed in series with the filaments of the diode control tubes 51, 52 and 53 and instead taps are provided on the output of transformer secondary 16 (corresponding to output transformer H) to obtain the desired reduced voltage. The taps are chosen so that the successive stages come on at still higher signal intensities than the preceding stages. The fourth pair of lamps 4 is of such a color as to predominate over the light of the second and third pairs. Of course, it will be apparent that more or less stages can be added, although it is believed that four basic colors are ordinarily sufficient in that they provide all the graduations and mixtures which occupy the transitions.

Various means may be used to display the colored lights involving both stationary and moving screen arrangements, as shown in my abovementioned patent. It will be apparent to those skilled in the art that there are an infinite number of presentation possibilities, giving room for a great play of artistic ingenuity.

In Figure 4, I have shown another type of tube which is connected between a controlling device of circuit C and is connected to a control device or circuit D. In other words, a tube or tubes of this type 3! may take the place of any or all of the tubes 3|--33 and 5l--53. In Figure 1, I have indicated connections f, g, h, and i, which correspond to the same connections of the tube 3| shown in Figure 4. In other words, as will be apparent, the tube 3| may be substituted for any or all of the tubes 3|, 32, and 33, or 52, and 53, and the connections will be as indicated. This figure shows what is believed to be one of the important generic features of novelty of the present invention that, as previously pointed out, consists in applying incoming current variations to the filament of a vacuum tube to provide a variable filament voltage in such a manner as to smooth out the variations when the current is taken off from the anode of such control tube. This is distinct from the ordinary idea of changing the grid characteristics of a tube for control purposes such as ordinarily effected in a radio receiver.

It is believed that Figure 4 somewhat diagrammatically represents one of the broader phases of the present invention. That is, I have been the first to impress a variable or interrupted current, whether of a direct or alternating type, upon the filament or heater of a thermionic tube in order to produce smoother or more gradual corresponding current variations in an anode circuit thereof. This principle as specifically applied herein involves the application of relatively sharp current changes in a circuit of relatively less power to the filament of a thermionic tube to effect more gradual current variations in a supplementary relatively higher power circuit as represented by the anode of the tube. manner, I can apply relatively higher power through an agency such as 44, see Figure 1, to the anode and produce variations therein by a supplemental circuit of lower power as represented by the filament of the tube. It will appear that I utilize thermal inertia of a filament or cathode of a tube to effect a gradual control over an anode current thereof; this is true whether the filament current, alternating or direct current varies in a continuous manner or is changed by switching it on and off. That is, the invention is not limited to the utilization of sound wave representing alternating currents.

The term filament as employed in the specification and claims hereof represents the filament or heater of a suitable control tube. It will be apparent that in a cathode type of tube the filament is represented by the heater element. Defined in another manner, the filament as used herein refers to the filament of a so-called filament type of tube as well as to the heater element of a heated cathode type of tube. For simplification of definition, when I refer to a filament in the claims I also include reference to the heater element of a heated cathode type of tube; when I refer to a coupling I also have reference to a connection and vice versa.

Although it will be apparent to those skilled in the art that the exact type of apparatus, tubes, and arrangements can be modified, and that variations can be made in the circuit elements and in their characteristics, capacities, resistances, etc., without departing from the spirit and scope of the invention and the novel principles therein involved, for the purpose of full illustration, I will give a schedule of elements which I have found satisfactory in circuits such as employed for the purpose of illustrating the invention: a represents output terminals of a radio receiver or other suitable source of current to be translated; fixed condensers II are about .5 microfarad (series blocking); resistance I2 is about .5 megohm; condenser I3 is approximately 12 microfarads; resistance I4 is about 250 ohms; I5 is a 6L6 vacuum tube; filter condenser I6 is In this about 16 microfarads, for approximately 325 volts plate current supplied by a connection e from secondary 23 and a ground tap on secondary 24; universal output transformers l1 and 16 are of a voltage reduction type, ratio about 450 or 500 to 1; current source 2| is a 110 volt alternating, such as provided in the home; 22 is the primary of a current supply transformer, 23, 24, and 25 being secondaries thereof; rectifier 23 is a full wave rectifierv such as an 80 vacuum tube; vacuum tubes 3|, 32, and 33 are of a suitable type such as 71--A; low inductance 34 preferably has an adjustable iron core, for example, 1000 turns No. 26 magnet Wire; low inductance 35 is similar to 34 but has about 800 turns; paper condenser 36 is about 4 to 6 microfarads (capacitive re- I actor) condenser 31 is about 2 to 3 microfarads;

resistances 38, 39, and 40 are about 2500 ohms, 2000 ohms, and 1500 ohms, respectively; lamp 4| is a 15 watt, volt, red or orange; lamp 42 is a 15 watt, 110 volt, green or yellow; lamp 43 is a 15 watt, 110 volt, blue or violet; stepuip autotransformer 44 is of a 1 to 2 ratio, providing approximately 220 volts for the circuit 30; audiotransformer 46 is of a 1 to 2 ratio; this is used if a 42 or 47 tube is employed as the amplifier I5; it is unnecessary if a 6L6 is used; loud speaker 41 is in parallel with output a from a radio receiver or other suitable current supply agency; vacuum tubes 5|, 52, and 53 may be of the 71-A type, or similar to the control tubes 3|, 32, and 33.

From the above description, it will appear that many substitutions, modifications, additions, and subtractions may be made in the illustrated circuit arrangements embodying my invention and that the principles of control involved particularly as applied to the filament of a vacuum tube may be employed in a wide field of electronics.

I claim:

1. In a visual indicator, low impedance apparatus for supplying sound wave audio frequency currents of a plurality of frequency ranges, a plurality of lights connected to said apparatus for indicating sound pitch variations of the currents of each of said plurality of ranges, a light transmitting globe, said plurality of lights being operably mounted in said globe, low impedance apparatus for supplying sound wave audio frequency currents of a plurality of amplitude ranges, a. plurality of lights connected to said last-mentioned apparatus for indicating sound variations of the currents of each of said plurality of amplitude ranges, said last-mentioned lights being positioned about said globe for producing a combined light effect therewith.

2. In a system of visually interpreting sound Wave representing audio frequency currents, a source of alternating audio frequency currents representing sound Waves, low impedance means connected to said source for supplying current of variable frequency, low impedance means connected to said source for supplying current of variable amplitude, a visual translating device connected to said variable frequency supply means, a visual translating device connected to said second-mentioned means, said second-mentioned visual device having a lamp adapted to light at a low amplitude of current being interpreted, and a progressive series of lamps adapted to light with variations in amplitude of the current supplied to said unit by said variable amplitude current supply means, said first-mentioned device having lights connected thereto and adapted to selectively light with variations of frequency of the current supplied thereto by said variable frequency current supply means.

3. In a system for interpreting sound-waverepresenting audio frequency currents, a source of audio frequency currents representing sound waves, a low impedance frequency selection device and an indicator, a thermionic control device having a filament and an anode, said frequency selection device being connected through the filament of said control device and being coupled to said source, said indicator having means operably coupled to the anode of said control device, so that said indicator will respond to audio frequency currents by-passed by said frequency selection device to said filament.

4. In a system utilizing electrical energy for visual interpretation of sound-wave-representing audio frequency currents, a source of soundwave-representing audio frequency signal currents, at least a pair of electron tubes having filaments and anodes, low impedance selector means connected to the filaments of said tubes and to said source and provided with means for impressing unequal portions of signal voltage upon the filaments in such a manner that each filament will reach a given heat at a different intensity level of sound-wave represented by the signal currents.

5. In a system for interpreting sound-waverepresenting audio frequency currents, a low impedance source of audio-frequency currents representing sound waves, at least a pair of ourrent-controlled indicators, each of said indicators being responsive to its own frequency range of current, thermionic means having filament and anode portions, said filament portions being connected to said source of audio frequency currents in such a manner that filament emission will be varied thereby, said indicators being operably connected to the anode portions to receive controlled frequency-selected space currents from said filament portions.

6. In a system utilizing electrical energy for visual interpretation of sound-wave-representing audio frequency currents, at thermionic control device having a filament and an anode, a low impedance controlling-signal-source of soundwave-representing audio frequency currents, said filament being connected to and heated by said low impedance source, a visual interpreting device, a source of supply voltage connected to said visual interpreting device, and means coupling said anod through said visual interpreting device to said source of supply voltage for controlling current through the visual interpreting device.

7. In a system utilizing electrical energy for visual interpretation of sound-wave-representing audio frequency currents, a source of soundwave-representing audio frequency currents, a low impedance circuit operably connected to said source for visually interpreting frequency variations of the current, and a circuit operably connected to said source for separately and visually interpreting intensity variations in current, so that a dual interpreting effect will be obtained.

8. In a system for indicating electrical current energy changes, a thermionic device having a filament and an anode, a low impedance source of input current energy connected to the filament, a current output circuit connected to the anode, indicator means connected in the current output circuit for directly indicating variations in emission current supplied to the anode from the filament, and a second indicator operably connected across said thermionic device and adapted to operate in an inverse manner with respect to said first-mentioned indicator device.

9. In a system for interpreting sound-waverepresenting audio frequency currents, a source of sound-wave-representing alternating audio frequency currents, a thermionic control device, a pair of indicator devices, said control device having a filament connected to and energized by said source of audio frequency currents, said thermionic device having an anode connected to one of said indicator devices for substantially directly indicating space currents supplied by said source, the other of said indicator devices being connected in shunt with said thermionic device for substantially indirectly indicating variations in space current energy supplied to the anode of said thermionic device, said lastmentioned device operating in an inverse manner with respect to said first-mentioned device.

10. In a system utilizing electric energy for interpreting sound-wave-representing audio frequency currents, a pair of thermionic devices, each device having a filament and an anode, a source of sound-wave-representing audio frequency currents, a low impedance frequency selection device, said frequency selection device and the filament of one of said thermionic devices being connected in series with each other and to said source, the filament of said secondmentioned thermionic device being connected to said source for energization thereby, indicator means connected in series with the anode of said first-mentioned thermionic device for indicating a frequency selected by said frequency selection device, and indicator means connected with the anode of said second-mentioned thermionic device to indicate amplitude variations in current supplied by said source.

ROBERT D. BURCHFIELD. 

